Process for production of uranium hexafluoride



i of UF6.

United PROCESS FOR PRODUCTION OF URANIUM HEXAFLUORIDE Robert Dudley Fowler, Baltimore, Md., assignor to'the United States of America as represented by the United States Atomic Energy Commission No Drawing. Application February 24, 1947 Serial No. 730,556

7 Claims. (Cl. 23-145) However, neither the treatment of U nor the treatment of the higher oxides of uranium such as uranium trioxide (U0 and uranium tritaoctoxide (U 0 with HF will yield UF Moreover, such treatment of U0 and U 0 instead of producing UR, tends to produce the oxyfluorides.

An object of the present invention therefore is to provide simple and economical methods for the production The essence of the invention is the conversion of uranium oxides to UP by the action of elemental carbon and a fluorinating agent such as elemental fluorine or cobaltic fluoride (C01 One method for the production of UP, is by the action of elemental fluorine on UF However, UF is not a commercially available material, and I have therefore aimed to provide a process which is applicable to the readily available oxides of uranium, such as U0 U0 and U 0 In accordance with the invention these oxides of uranium may be reduced with carbon and simultaneously reacted with a fluorinating agent to convert them to uranium hexafluoride.

A process in accordance with the invention is as follows:

Finely divided carbon such as sugar carbon or charcoal or Norit is mixed with finely divided U 0 using a proportion of the carbon to the oxide about 50% in excess of that theoretically required (according to the reaction U O +4C+9F =3UF +4CO to combine with all of the oxygen as C0 The mixture is placed in a copper boat or tray in a copper or nickel oven and heated to from 400 C. to 500 C., e. g. by wrapping the oven with electrical resistance heating elements. Fluorine gas free of HF, 0 and H 0 is passed into the oven and the gas leaving the oven is run through a trap or condenser cooled to 70 C. to collect the UP formed. The yield of UP based upon the uranium content of the oxide used is from 95 to 100%, and the utilization of the fluorine gas supplied to the reaction chamber is highly efficient if the rate of flow of the gas compared to the exposed surface of the mixture of the uranium oxide and carbon is not excessive. For instance the rate of supply of fluorine gas may be about 100 cc. per minute for a charge of about 3 kilograms of the oxide spread in a layer about one-half inch deep.

In the above described process any of the oxides of uranium i. e., U 0 U0 or U0 or mixtures thereof may Patented Nov. 4, 1958 The UP thus produced is run through a trap or condenser cooled to C. to collect the UF formed.

The CoF for this process may be made by treating CoF with elemental fluorine, e. g., by placing the CoF in a copper boat in a copper reaction chamber, heating to about 200 C. and passing fluorine gas into the chamber. An advantage of this process is that the fluorine gas, produced for instance by the electrolysis of an acid fluoride or a mixture or a combination of an alkali metal fluoride and hydrofluoric acid, need not be purified with respect to HF before it is used. Another advantage of the above procedure is that after heating the mixture of uranium oxide, carbon and CoF and expelling the UF the residue of CoF may be treated with fluorine, as described above, to reconvert it into 00F, and the latter used again in a repetition of the process.

Other metal fluorides, such as silver difluoride (AgF bismuth pentafluoride (BiF and ceric fluoride (CeF may be substituted for the CoF in the above process, but practically, so far as I have tested them, CoF, is the most satisfactory.

This application is a continuation-in-part of my copending application, Serial No. 475,851, filed February 13, 1943, now Patent No. 2,810,626.

As many embodiments may be made of this inventive concept and as many modifications may be made in the embodiments hereinbefore set forth, it is to be understood that all matter described herein is to be interpreted merely as illustrative and limited only by the scope of the appended claims.

I claim:

1. Process for the production of uranium hexafluoride which comprises contacting an oxide of uranium simultaneously with elemental carbon and elemental fluorine at 400 C. to 500 C., and recovering the uranium hexafluo ride thereby produced.

2. Process as defined in claim 1 in which the oxide of uranium is U 0 3. Process as defined in claim 1 in which fluorine gas is contacted with an intimate mixture of the uranium oxide and carbon.

4. Method for the production of uranium hexafluoride which comprises simultaneously heating at 300 C. to 5 00 C. a mixture of an oxide of uranium and elemental carbon in the presence of a fluorinating agent selected from the group consisting of elemetnal fluorine, cobaltic fluoride, silver difluoride, bismuth pentafluoride, and ceric fluoride, and recovering the uranium hexafluoride thereby produced.

5. Method for the production of uranium hexafluoride which comprises reducing an oxide of uranium with elemental carbon and simultaneously reacting it at 300 C. to 500 C. with a fluorinating agent selected from the group consisting of elemental fluorine, cobaltic fluoride, silver difluoride, bismuth pentafluoride, and ceric fluoride, and recovering the uranium hexafluoride thereby produced.

6. A process for producing UF from U 0 which comprises heating a mixture of U 0 and carbon to from 400 to 500 C. while passing fluorine gas over said mixture, and recovering the uranium hexafluoride thereby produced.

7. A process for'producingUF from U 0 which cornprises heating a mixture of U 0 carbon and CoF at 7 300 to 500 C. and recoyering the uraniuni hexafluoride thereby produced. 7

References'Cited in the file of this patent Mellor: Treatise on Inorganic and Theoretical Chemistry, pp. 74, 75, vol. 12.

Mellor: Treatise on Inorganic and Theoretical Chemistry, vol. 5, pp. 890, 891.

Katz et al.: The Chemistry of Uranium, pp. 399, 447, 448 (1951) publ. by McGraw-Hill Book Co., New York, N; Y. 

1. PROCESS FOR THE PRODUCTION OF URANIUM HEXAFLUORIDE WHICH COMPRISES CONTACTING AN OXIDE OF URANIUM SIMULTANEOUSLY WITH ELEMENTAL CARBON AND ELEMENTAL FLUORINE AT 400*C. TO 500*C., AND RECOVERING THE URANIUM HEXAFLUORIDE THEREBY PRODUCED. 